Ozone has been known to be useful for inhibiting, reducing and/or eliminating, among other things, biomass, mold, mildew, algae, fungi, bacterial growth and scale deposits in various aqueous solution systems. Ozone, for example, has been used as a biocide for the treatment of drinking water and as a phenols and cyanide removing means in the treatment of industrial wastewater streams. It may also be used in killing zebra mussels but it is particularly useful for oxidizing organic or inorganic contaminants in cooling water systems or water recycling systems. The effectiveness of ozone in each system, however, is adversely affected by its low solubility and low utilization in aqueous solutions.
Bubbling ozone directly into the water to be ozonated, i.e. cooling water in a tower basin, has been used to dissolve ozone in aqueous solutions. Such a technique, however, does not dissolve ozone sufficiently in aqueous solutions because the ozone bubbles rise before a substantial amount of ozone can be dissolved into aqueous solutions. When the quantity of dissolved ozone in the cooling water, for example, is less than that required to treat a cooling water system, the piping and process heat exchanger of the cooling water system may become clogged due to the uninhibited scale deposits and biological growth.
Injecting ozone into a recycling aqueous stream which is to be mixed with an aqueous solution to be ozonated has also been utilized to dissolve ozone in the aqueous solutions. In a cooling water system, for instance, ozone is injected into a side stream conduit which circulates a portion of the cooling water. The ozone injected water in the side stream conduit is then mixed with the cooling water in a tower basin, thereby ozonating the cooling water before its use in process heat exchange means. The cooling water system designed to operate in such a manner is described, for example, in U.S. Pat. No. 4,172,786 and Journal of the Cooling Tower Institute, vol 8, No. 2, 1987. Although this system dissolves more ozone than a system designed to feed ozone directly into the cooling water in the tower basin, much of the ozone injected is still gassed off to the atmosphere and/or is converted to oxygen rather than being dissolved in the cooling water. Therefore, this system is not sufficiently efficient in dissolving ozone, thus requiring the use of a large amount of ozone. There is a need to dissolve an increased amount of ozone in aqueous solutions, not only to minimize the amount of ozone used but also to provide sufficiently ozonated aqueous solutions for given systems.
Accordingly, it is an object of the present invention to dissolve an increased amount of ozone, thereby decreasing the amount of ozone needed to produce sufficiently ozonated aqueous solutions for given systems.
It is another object of the present invention to minimize the conversion of ozone to oxygen during the ozonation of aqueous solutions and reduce the emission of ozone to the atmosphere to avoid any detrimental atmospheric effects.